Relationship of Allergen-Specific IgE Antibodies, Skin Prick Tests and Allergic Disorders in Unselected Adolescents

The relationship between serum levels of allergen-specific IgE (RAST) and skin prick test reactivity and allergic disorders was evaluated in 137 subjects randomly selected from an adolescent population. All subjects were prick tested with six common allergens, interviewed and physically examined. In addition, serum was collected for RAST analysis with three to six allergens. At least one positive RAST result (score 1-4) was observed in 40% and at least two positive RASTs in 22% of the subjects. Boys experienced more RAST reactions and generally with higher scores than girls. For instance, 26% of boys but only 11% of girls were RAST positive to timothy grass pollen. The correlation between prick test and RAST results was better with pollens than with house dust and animal epithelia. When the test results were discordant, the skin test was usually positive and RAST negative. Many of the small skin reaction (weal diameter 3-4 mm) were accompanied by a negative RAST. Respiratory allergy was closely connected with both positive skin test and RAST reactivity, while atopic dermatitis was less related. In 17% of the adolescents positive skin tests and in 14% positive RASTs occurred in the absence of any allergic symptoms. We conclude that a positive RAST score 3-4 to inhaled allergens is a strong indicator of clinical allergy but low scores 1-2 are frequently found in healthy young people.